This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Chd1 is a chromatin remodeler that participates in gene transcription by manipulating nucleosome structure. By sliding nucleosomes along DNA, Chd1 is known to generate evenly-spaced nucleosomal arrays, and we have found that the Chd1 DNA-binding domain is essential for sensing the relative distances between nucleosomes. The Chd1 DNA-binding domain binds DNA in a sequence-nonspecific fashion, and current questions include (1) how the DNA-binding domain interacts with DNA just outside the nucleosome core, (2) whether binding is coupled to conformational changes in the DNA duplex, and (3) whether DNA binding by Chd1 would be expected to be compatible with DNA associating with the nucleosome (i.e. promote release of the DNA-binding domain). We currently have crystals of the yeast Chd1 DNA-binding domain in complex with a 12mer DNA duplex that diffract to better than 2.3 angstrom resolution. We have grown small SeMet crystals and hope to obtain phases and solve the structure.